/*
 * Copyright 2013 Sigurd Randoll.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.digiway.rapidbreeze.server.model.download;

import de.digiway.rapidbreeze.shared.rest.download.DownloadStatus;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 *
 * @author Sigurd
 */
class DownloadStatusHandler {

    private DownloadStatus previousStatus;
    private DownloadStatus currentStatus;
    private Exception errorException;
    private List<DownloadListener> listeners;
    private Object source;

    DownloadStatusHandler(Object source) {
        this.source = source;
        this.listeners = new CopyOnWriteArrayList<>();
        this.currentStatus = DownloadStatus.WAITING;
    }

    public void addListener(DownloadListener listener) {
        listeners.add(listener);
    }

    public void removeListener(DownloadListener listener) {
        listeners.remove(listener);
    }

    public void switchToPreviousStatus() {
        newStatus(previousStatus);
    }

    public void newStatus(DownloadStatus newStatus) {
        newStatus(newStatus, null);
    }

    public void newException(Exception ex) {
        newStatus(DownloadStatus.ERROR, ex);
    }

    public Exception getErrorException() {
        return errorException;
    }

    public DownloadStatus getCurrentStatus() {
        return currentStatus;
    }

    private void newStatus(DownloadStatus newStatus, Exception newException) {
        previousStatus = currentStatus;
        currentStatus = newStatus;
        errorException = newException;
        DownloadEvent event = new DownloadEvent(source, previousStatus, newStatus, newException);

        for (DownloadListener listener : listeners) {
            listener.onDownloadStatusChange(event);
        }
    }
}
